Work-table on machines for processing metal

ABSTRACT

A work-table having a table panel, a support element which supports the table panel across a load bearing dimension of the panel, and itself defines over the same dimension with a bottom part an oil chamber the oil in which will support the support element and panel, via an vertically displaceable separation member. This separation member is in the form of a number of pistons, displaceably arranged in bores of a plate between support element and oil, or in the form of a diaphragm.

Hanni et al.

WORK-TABLE ON MACHINES FOR PROCESSING METAL [75] Inventors: Eduard Hanni, Zofingen; Walter Gygli, Niderpipp, both of Switzerland [73] Assignee: Hammerle A.G. Maschinenfabrik,

Zofingen, Switzerland [22] Filed: Dec. 18, 1972 [21] Appl. No.: 316,016

[30] Foreign Application Priority Data Dec. 22, l97l Switzerland 11026/71 [52] US. Cl. 267/130, 267/119 [51] Int. Cl Fl6f 7/00 [58] Field of Search 267/130, 119,75

[56] References Cited UNITED STATES PATENTS 2,842,357 7/1958 Williamson 267/l 19 [451 Aug. 13, 1974 3,677,04l 7/l972 Dokoupil 267/130 Primary Examiner-James B. Marbert Attorney, Agent, or Firm-Abraham A. Saffitz [57} ABSTRACT A work-table having a table panel, a support element which supports the table panel across a load bearing dimension of the panel, and itself defines over the same dimension with a bottom part an oil chamber the oil in which will support the support element and panel, via an vertically displaceable separation member. This separation member is in the form of a number of pistons, displaceably arranged in bores of a plate between support element and oil, or in the form of a diaphragm.

2 Claims, 2 Drawing Figures WORK-TABLE ON MACHINES FOR PROCESSING METAL The present invention relates to a work-table on machines for processing metal in sheet or plate form, more particularly press brakes. A frequent occurrence in high-pressure press brakes is that while a work-piece is being dealt with, the push-rod bends up and the worktable bends down, with the result that there remains between the top tool and the bottom tool a gap which is larger towards the centre than at both ends; machining accuracy is therefore impaired.

In order to compensate for such inaccuracies, a centring plate has been proposed, having a curvature strip which is transversely adjustable on a keyway and which is retained at both ends on the bottom part of the centring plate. This system provides fairly accurate compensation for bending, but with the great disadvantage that re-adjustment is required upon any change of material or tools or pressure.

US. Pat. No. 3,682,465 relates to a work-table on machines for processing metal in sheet or plate form, more particularly press brakes. In order to avoid the occurrence of a gap between the push-rod and the work-table in the middle of the latter this Patent provides the work-table with a work-table panel, and a support element having an inverted T-shape mounted in a part with the head of the T cooperating with abutments on the bottom part to limit upward movement of the supportelement, said support element also having lateral sealing elements for making sealing engagement with the bottom part and vertically displaceable therein and defining therewith a chamber for receiving oil on which the support element will rest.

Such a work-table has proved very reliable and it has been shown that very precise work can be performed with a machine equipped with such a work-table. However, it had to be recognized as disadvantageous that the support element and the member for guiding the support element has to be machined with a very high degree of accuracy in order to avoid any oil leaks. In particular, a work-table for a very long press brake or a work-table subjected to very high pressure, has been shown as very expensive in construction.

It is an object of this invention to provide a worktable for machines for processing metal in sheet or plate form, more particuarly press brakes, which compensates automatically for bending of this kind or ensures that no such bending can occur.

It is further object of the present invention to provide an improved work-table of the previously mentioned kind, working on the same principle.

It is still a further object of the invention to provide a work-table of such a kind which is much less expensive in construction and is well suited for long metal processing machines operated with high working pressure.

According to the present invention, this is achieved on a work-table as described above by providing at least one vertically displaceable separation member between the support element and the oil.

In order that the invention may be well understood there will now be described two embodiments thereof, given by way of example only, reference being made to the accompanying drawings, in which:

FIG. 1 is a diagrammatic view in cross-section of a first embodiment of the work-table according to the invention, and

FIG. 2 is a similar view of a second embodiment.

FIG. 1 is a diagrammatic view in cross-section of a first embodiment, comprising a table panel 1 for supporting a tool 2. Panel 1 rests on a support element 3 which extends over the whole length of panel 1 and in cross-section resembles an inverted T; element 3 is mounted for vertical displacement in a member 4. The interior of the members 4 in cross-section resembles an inverted T corresponding to that of the element 3, but the depth of the cross piece of the T of the interior of member 4 is greater than that of the element 3 to define between element 3 and member 4 a chamber.

A plate 5 is mounted in this room, extending substantially parallel to the lower surface of element 3 and dividing the room below element 3 into two parts. The plate 5 is provided with a number of circular bores 6 in which a corresponding number of pistons 7 are inserted. Each of the pistons 7 is equipped with two sealing rings 8 in order to seal the two parts of the room below element 3 from each other. The pistons 7 are displaceable in the bores 6 in vertical direction.

The lower part of the room below element 3 is filled with oil 9 under high pressure and the piston 7 rest against the surface of this oil bed with their lower frontal face. The element 3 rests against the upper frontal faces of pistons 7, which extend in the upper part of the room below element 3.

Due to the high pressure in the oil 9, and when the table is not in use, the oil forces the element 3 upwardly until the cross piece of the element 3 contacts the upper wall of the cross piece of the interior of member 4 which thus forms an abutment limiting upward movement of the element 3.

When downwards pressure is applied to panel 1, the panel descends slightly together with element 3 and the pressure is transmitted to the oil in chamber 9 via pistons 7. If the pressure, e.g., at the centre of panel I is greater than at the ends thereof, the back-pressure at the centre of the panel is correspondingly greater than at the ends due to the compensating action of the oil cushion in chamber 9, i.e., pressure distribution is completely uniform, Consequently, bending cannot occur and so a workpiece can be processed very accurately.

A second embodiment is shown in FIG. 2, comprising a table panel I for supporting a tool 2. Panel 1 rests on a support element 3 which extends over the whole length of panel 1 and in cross-section resembles an inverted T; element 3 is mounted for vertical displacement in a guiding member 10 arranged within a basic member 4. The interior of the member 10 in crosssection resembles an inverted T corresponding to that of the element 3. The lower, inner surface of the basic element 4 is provided with a recess extending nearly over the whole length of it, which is filled with oil 9. The surface of this oil bed 9 is covered by a elastic diaphragm 11, the size of which is somewhat larger than the area of the surface of the oil bed 9. The lower face of the guiding member 10 contacts a part of the surface of the diaphragm I1 and holds it firmly in place, making thereby a scaling engagement between abutments on member 4, diaphragm II and lower face of guiding element 10. v

The lower face of element 3 rests on the upper surface of diaphragm 11, while the lower surface of the latter rests on the surface of the oil bed 9.

In a similar manner as described in connection with FIG. 1, the oil, which is again under high pressure, forces the element 3 upwardly until the cross piece of the element 3 contacts the upper wall of the cross piece of the interior of member which thus forms an abutment limiting upward movement of the element 3. When downwards pressure is applied to panel 1, the panel descends slightly together with element 3 and the pressure is transmitted via diaphragm 11 to the oil in chamber 9. If the pressure, eg at the centre of panel 1 is greater than at the ends thereof, the back-pressure at the centre of the panel is correspondingly greater than at the ends due to the compensating action of the oil cushion in chamber 9, i.e. pressure distribution is completely uniform. Consequently, bending cannot occur and so a workpiece can be processed very accurately.

The main advantages of these improved embodiments are as follows:

There are no sealing problems, even at very long worktables or with machines operating under very high pressures.

The machining of the parts of the work-table is much less complicated and must not be very precise.

After a long period of use, there are only minor parts to exchange (i.e., pistons 7, diaphragm 11) in order to get full reliability as with a new work-table.

What We claim is:

1. A work-table comprising a table panel, a table base, an inverted T-shaped support element, said table base and said support element extending over the entire length of said panel, said support element supporting this load bearing dimension of the panel;

said T-shaped support element itself defining over the same length dimension with said table base an oil chamber;

abutment means on said table base for mounting said T-shaped support element so that said T-shaped support element is vertically displaceable and is mounted in said table base with the head of the T cooperating with said abutments on said table base to limit upward movement of said support element;

vertically displaceable separation means for covering said chamber on which said support element rests;

a piston plate fixed in spaced relation below the parallel to the lower surface of said support element, with said lower surface of said support element resting on the upper surface of pistons mounted on said piston plate;

circular openings in said piston plate for mounting pistons thereon;

oil filling said chamber, the surface of the oil coming up to the lower surface of the piston; and,

sealing rings for sealing said pistons of the inner surface of the openings in said plates, said sealing rings preventing the flow of oil above the lower surface of said pistons and separating the free space above the plate from the oil filled space below the plate.

2. A work-table comprising a table panel, a table base and an inverted T-shaped support element said table base and said support element extending over the entire length of said panel and said support element supporting this load bearing dimension of the panel;

said T-shaped support element itself defining over the same length dimension with said table base and an oil chamber;

abutment means on said table base for mounting said T-shaped support element so that said Tshaped support element is vertically displaceable and is mounted in said table base with the head of the T cooperating with said abutments on said table base to limit upward movement of said support element;

vertically displaceable separation means for covering said chamber on which said support element rests;

oil filling said chamber, the surface of the oil substantially coming up to the lower surface of said support element;

an elastic, impermeable diaphragm disposed directly above the surface of the oil having said support element resting on the surface of said diaphragm; and,

sealing means for fixing said diaphragm in said table base, said sealing means sealing said oil filled chamber to prevent oil therein from moving above said diaphragm. 

1. A work-table comprising a table panel, a table base, an inverted T-shaped support element, said table base and said support element extending over the entire length of said panel, said support element supporting this load bearing dimension of the panel; said T-shaped support element itself defining over the same length dimension with said table base an oil chamber; abutment means on said table base for mounting said T-shaped support element so that said T-shaped support element is vertically displaceable and is mounted in said table base with the head of the T cooperating with said abutments on said table base to limit upward movement of said support element; vertically displaceable separation means for covering said chamber on which said support element rests; a piston plate fixed in spaced relation below the parallel to the lower surface of said support element, with said lower surface of said support element resting on the upper surface of pistons mounted on said piston plate; circular openings in said piston plate for mounting pistons thereon; oil filling said chamber, the surface of the oil coming up to the lower surface of the piston; and, sealing rings for sealing said pistons of the inner surface of the openings in said plates, said sealing rings preventing the flow of oil above the lower surface of said pistons and separating the free space above the plate from the oil filled space below the plate.
 2. A work-table comprising a table panel, a table base and an inverted T-shaped support element said table base and said support element extending over the entire length of said panel and said support element supporting this load bearing dimension of the panel; said T-shaped support element itself defining over the same length dimension with said table base and an oil chamber; abutment means on said table base for mounting said T-shaped support element so that said T-shaped support element is vertically displaceable and is mounted in said table base with the head of the T cooperating with said abutments on said table base to limit upward movement of said support element; vertically displaceable separation means for covering said chamber on which said support element rests; oil filling said chamber, the surface of the oil substantially coming up to the lower surface of said support element; an elastic, impermeable diaphragm disposed directly above the surface of the oil having said support element resting on the surface of said diaphragm; and, sealing means for fixing said diaphragm in said table base, said sealing means sealing said oil filled chamber to prevent oil therein from moving above said diaphragm. 